Acoustical unit with attenuation means



Feb. 20, 1962 w, G. KEMP 3,021,915

ACOUSTICAL UNIT WITH ATTENUATION MEANS Filed April 6, 1959 1,2 i F|G.|.

INVENTOR. WILLIAM G. KEMP ATTORNEYS ,c 3,021,915 Patented Feb. 20, 1962United States Patent Olice 3,021,915 ACOUSTICAL UNIT WITH ATTENUATIONMEANS William G. Kemp, 2275 E. Hammond Lake Drive, Pontiac, Mich. FiledApr. 6, 1959, Ser. No. 804,392

4 Claims. (Cl. 181-33) This linvention refers generally to acousticalpanels for room ceilings and the like yand more particularly to anacoustical panel having means for refllecting sound waves passingthrough the sound absorbing portion of said panel back into said soundabsorbing portion.

One of the prime purposes for the installation of an acoustical ceilingisof course to -absorb as much of the sound waves impinging on saidceiling as is possible. In the past sound waves coming in contact withan acoustical panel passed through said panel including the soundabsorbing means therein in a more or less direct path. The lowering ofthe sound level by acoustical panels has in 'the past therefore dependedto a great extent on the thickness of the sound absorbing means sincethe sound waves pass in one side of the absorbing means and out theother. With the usual sound absorbing means the sound passing out of theabsorbing means after having passed therethrough is still objectionable.This is especially true in the case of suspended acoustical ceilingswhere the chamber above thefsuspended ceiling acts as a duct to spreadsound waves received through the only partly eifective acousticalmaterial into areas where the sound waves are objectionable. Through theuse of an acoustical panel having an attenuating pan attached to theback thereof to reflect the sound Waves passing through the soundabsorbing means back into the sound absorbing means many of theobjectionable qualities of previous acoustical panels can be eliminated.

One of the essential objects of this invention is therefore to providean acoustical panel having means for reflecting sound into a soundabsorbing means.

Another object is to provide improved means to attenuate sound waves ina suspended ceiling system.

Another object is to provide an improved acoustical panel which may beinstalled and removed as a complete unit.

Another object is -to provide an acoustical panel through which soundtransfer will be a minimum.

Another object is to provide an acoustical panel which is simple inconstruction, easy to manufacture and efficient 1n use.

Other objects, advantages and novel details of construction of thisinvention will be made more apparent as this description proceeds,especially when considered in connection with the accompanying drawingswherein:

FIGURE 1 is -a plan view of the normally exposed surface of anacoustical panel according to this invention.

FIGURE 2 is a side view of the panel of FIGURE l.

FIGURE 3 is an enlarged longitudinal section of the panel in FIGURE 1along the line 3 3.

FIGURE 4 is an end view of the panel of FIGURE 1.

FIGURE 5 is an enlarged cross section of the panel of FIGURE 1 along theline 5 5.

FIGURE 6 lis -an enlarged perspective of one end of the panel of FIGURE1 partly in section to better show the construction of said panel.

The invention consists of a rigid substantially at supporting pan 2having perforations 4 therein and upturned sides 6, 8, 10 and 12, asound absorbing material 14 inside of pan 2 and -an attenuating pan 16placed on top of the sound absorbing material 14 and adapted to connectwith pan 2 whereby sound waves passing through pan 2 and sound absorbingmeans 14 and impinging on attenuating pan 16 are reflected back intosound absorbing means 14.

The supporting pan 2 in the embodiment of the invention shown in FIGURESl-6 is a at rigid pan 2 of rectangular cross section. The pan 2 isapproximately three times as long as it is wide and is divided intosquare sections by grooves 18. The square sections have perforations 4therein covering substantially the entire surface thereof. The pan 2 hassides 6, 8, 10 and 12 which have been formed by turning up the Ifoursides of a at rectangular sheet of rigid material. Sides 6, 8, 10 and 12are provided with grooves 20 parallel to the plane of pan 2 whichproduce shoulders 22 on the interior of sides 6, 8, 10 and 12, Theshoulders 22 -are used to secure the attenuation pan 16 to thesupporting pan 2 in a manner later described. The sides 6, 8, 10 and 12of pan 2 have cut out sections 24 at third points along the lengththereof and cut out sections 26 at the four corners thereof tofacilitate connection of the supporting pan 2 in a complete acousticalsystem such as a suspended ceiling (not shown). 'The pan 2 may be madeof anyrigid material such as enameled metal or plastic. The surface ofthe material should be capable of being made a variety of colors andshould be easily cleaned.

Sound absorbing material 14 which is placed inside of supporting pan 2may be a mat of synthetic material such as fine plastic or glass fibresor it may be wool or wood fibre. The material shown at 14 is arectangular mat which substantially fills supporting pan 2. A loosesound absorbent material may also be used. According to this 'inventionno particular requirement as to the quality or quantity of soundabsorbent material to be used is made.

The attenuating pan 16 provided according to this invention is a at panas shown in FIGURES 3, 5 and 6. The pan 16 may be formed from a flatrectangular sheet of material by bending the edges thereof down to forman obtuse angle as shown at 28 and then turning the bent down edges upto form lips 30. The attenuation pan 16 may be of any material capableof retaining its form and capable of reflecting sound waves impingingthereon. Metal or plastic material may be used for the attenuation panwith acceptable results. The function of the attenuation pan 16 is toreflect sound passing through the supporting pan 2 and the soundabsorbing material 14 and impinging on pan 16 back into material 14where it is further absorbed.

The supporting pan 2 and the attenuation pan 16 may be manufactured byknown means such as the stamping of sheet metal or the molding ofplastic. The sound absorbing material may be produced by pressingfibrous material into mats by a process also well known. The mat orother form of sound absorbing material 14 is then placed in support pan2. Attenuation pan 16 is placed on top of material 14 and the edges ofmaterial 14 are compressed as shown at 32 by the edges of the pan 16.The lips 30 of the pan 16 are forced over shoulders 22 on sides 6, 8, 10and 12 thereby locking the support pan 2, the sound absorbing means 14and the attenuation pan 3 in assembly. The assembly as shown best inFIGURE 6 may be installed or removed from an installation as a unit.

In use a plurality of the assembled panels may be arranged to form forexample a suspended ceiling. The hanger wires, channel support means andclips necessary for such a system are well known and form no part ofthis invention and therefore are not shown. With the suspended ceilingin place sound waves within the area covered by said ceiling will strikeagainst the panels. The sound waves will pass through the support pan 2and through the absorbing means 14 where they will to a large extent beattenuated. The sound passing through the absorbing material 14 mayhowever still be objectionable. In the usual acoustical system suchsound is allowed to pass into the space above the suspended ceiling andtravel through this space to other areas where it is unwanted.

According to this invention however the sound waves passing through thesound absorbing material 14 strike attenuation pan 16 and are reflectedback into the material 14 where they are further absorbed. The pan 16thus contines the sound to a great extent to the area where it iscreated and causes the sound to be further deadened by passage throughthe absorbing material 14 again.

The drawings and the foregoing specification constitute a description ofthe improved acoustical panel in such full, clear, concise and exactterms as to enable any person skilled in the art to practice theinvention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

l. An acoustical panel, comprising a first substantially flat rigidrectangular pan for supporting sound absorbing members, said pan havinga plurality of perforations therein and also having the edges thereofturned up to form sides, each of said sides having a groove thereinparallel to and spaced from the plane of said pan providing an interiorshoulder on said sides, a rectangular sound absorbing mat within andsubstantially filling said pan, and a second rectangular pan `of soundreflecting material covering said mat, said second pan having the edgesthereof depending downward at an obtuse angle which terminate in lipsextending behind said interior shoulders on the sides of said firstrectangular pan to lock said two pans and said sound absorbing mat inassembly, whereby sound waves passing through the said first pan and thesound absorbing mat and impinging on said second pan are reflected backinto said mat.

2. An acoustical panel, comprising a first substantially flat rigidrectangular pan for supporting sound absorbing members, said pan havinga plurality of perforations therein and also having the edges thereofturned up to form sides, each of said sides having a groove thereinparallel to and spaced from the plane of said pan providing an interiorshoulder on said sides, a rectangular sound absorbing mat ofcompressible slightly resilient material within and substantiallyfilling said pan to a depth above the grooves in said sides, and asecond rectangular pan of sound reflecting material covering said mat,said second pan having edges depending downward at an obtuse angle whichterminate in lips extending behind said interior shoulders on the sidesof said first rectangular pan, compressing the edges of the soundabsorbing material and locking said two pans and said sound absorbingmat in assembly, whereby said sound absorbing mat urges said lips intoengagement with said shoulders and sound waves passing through saidfirst pan and the sound absorbing mat and impinging on said second panare reflected back into said mat.

3. An acoustical panel comprising a first substantially flat rigid panfor supporting sound absorbing members, said pan having a plurality ofperforations therein and also having opposite edges thereof turned up toform sides, each of the sides having a groove therein parallel to andspaced from the plane of the pan providing an interior shoulder on thesides, a sound absorbing mat within and substantially filling said panand a second pan of sound reflecting material covering said mat, saidsecond pan having opposite edges thereof depending downward at an obtuseangle which terminate in lips extending behind the interior shoulders onthe sides of the first pan to lock the two pans and the sound absorbingmat in assembly, whereby sound waves passing through the first pan andthe sound absorbing mat and impinging on the second pan are reflectedback into the mat.

4. An acoustical panel comprising a first substantially flat rigid panfor supporting sound absorbing members, said pan having a plurality ofperforations therein and also having opposite edges thereof turned up toform sides, each of the sides having a groove therein parallel to andspaced from the plane of the pan providing an interior shoulder on thesides, a sound absorbing mat within said pan and a second pan of soundreflecting material covering said mat, said second pan having oppositeedges depending downward which terminate in lips extending behind theinterior shoulders on the sides of the first pan to lock the two pansand the sound absorbing mat in assembly, whereby sound waves passingthrough the first pan and the sound absorbing mat and impinging on thesecond pan are reflected back into the mat.

References Cited in the file of this patent UNITED STATES PATENTS1,726,500 Norris Aug. 27, 1929 1,832,741 Sersen et al Nov. 17, 19311,929,751 Macdonell Oct. 10, 1933 1,998,422 McNeil et al. Apr. 16, 19352,007,374 Kuehne July 9, 1935 2,180,945 Morey Nov. 21, 1939 2,278,331Meyercord Mar. 31, 1942 2,281,109 Olsen Apr. 28, 1942 2,308,869 EckardtJan. 19, 1943 2,579,157 Price et al Dec. 18, 1951

